Ethanol (C2H5OH) melts a - 144 oC and boils at 78 °C. The enthalpy of fusion of ethanol is 5. 02 kj/mol, and its enthalpy of vaporization is 38. 56 kj/mol. The specific heats of solid and liquid ethanol are 0. 97j/g - k and 2. 3 j/g - K, respectively.

(a) How much heat is required to convert 42. 0 g of ethanol at 35 °C to the vapor phase at 78 °C?

(b) How much heat is required to convert the same amount of ethanol at - 155 oC to the vapor phase at 78 °C?

Answer:

The answer is 21.5 L

Explanation:

The reason behind the acceptance of Darwin's theory is D It is supported by practical evidence and examples.

The theory of evolution proposed by Charles Darwin is a well sustained model that explains how animals change in order to adapt to an ever-changing enviroment, which is supported by scientific evidence and observations.

Therefore, with this data, we can see that the theory of evolution proposed by Charles Darwin is well sustained by evidence obtained from experimentation and also observations of the natural world.

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Answer: K

Explanation: as we move down the group new shells are added and this increases the distance between the outermost electron and the nucleus.

The nuclear product of radioactive decay is called the daughter nuclide.

True

Radioactivity is a phenomenon in which particles such as alpha, beta and gamma rays are emitted from unstable atomic nuclei. This is due to the fact that the nucleus is unstable and requires a rearrangement of its protons and neutrons. Radioactive isotopes can be found in nature, or they can be artificially created. Radioactivity has many useful applications, such as medical imaging, cancer treatments, smoke detectors, and nuclear energy. It also has some potential dangers, such as radiation exposure and the risk of nuclear disasters.

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The elements that are nitrogen, oxygen and fluorine all of them exist as diatomic gases at room temperature.

There are total seven diatomic elements that are written as follows: hydrogen (H), nitrogen (N), oxygen (O), fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). The formation of diatomic gases is done by making up two atoms of the same gas. For example, the formula for nitrogen gas is N2, the formula for oxygen gas is O2 and the formula for Fluorine gas is F2. The word diatomic has other synonym which is known as heteronuclear. The position of all these three elements in the periodic table is different so their electronegativities, the only common factor is that they exist as a gas.

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In a container, the pressure of hydrogen sulfide gas is 267.4 torr.

The force of all gas particle/wall collisions divided by the area of the wall is defined as pressure (P): Pressure is one of the primary observable quantities of this phase of matter; it is exerted by all gases. The amount of force exerted per area is described as pressure. Pressure is defined as force divided by area. The pressure from snow on a roof, for example, would equal the weight of the snow divided by the area of the roof. In chemistry, pressure is often generated by gases. When you blow up a balloon, you fill it with gas.

Here,

pressure of hydrogen sulfide gas= 35650 Pa

1 torr=133.33 Pa

=35650/133.33

=267.38 torr

The pressure of hydrogen sulfide gas in a container is 267.4 torr.

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Answer:

3 (e

Explanation:

The empirical formula for this compound containing 59.94 % carbon, 13.44 % hydrogen, and 26.62 % oxygen by mass is C3H8CO.

Given the % of carbon = 59.94%

The % of hydrogen = 13.44%

The % of oxygen = 26.62%

If a percentage is provided, we will assume that the entire mass is 100 grams. As a result, each element's mass is equal to the percentage indicated. Then

the mass of carbon (m1) = 59.94g

The mass of hydrogen (m2) = 13.44g

The mass of oxygen (m3) = 26.62g

We know the molar mass of C = 12 g/mole

The Molar mass of H = 1 g/mole

The Molar mass of O = 16 g/mole

The moles of carbon = 59.94/12 = 4.995

The moles of hydrogen = 13.44/1 = 13.44

The moles of oxygen = 26.62/16 = 1.664

Divide each mole value by the lowest computed mole number to get the mole ratio.

For C = 4.995/1.664 = 3 , For H = 13.44/1.664 = 8 and For O = 1.664/1.664 = 1. Then the empirical formula = C3H8CO

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A chloride of rhenium contains 63.6% rhenium.  the formula of this compound  is Re2Cl3.

The chemical trirhenium nonachloride has the formula ReCl3, which is occasionally also written as Re3Cl9. It is a hygroscopic solid that is dark red in color and insoluble in common solvents. The substance is significant in the development of inorganic chemistry since it was the first cluster compound to have metal-metal links. [1] It serves as the raw ingredient for the production of various rhenium complexes. Rhenium is an atomic number 75 chemical element with the symbol Re. It is a heavy, third-row transition metal in group 7 of the periodic table that is silvery-gray in color. Rhenium is one of the rarest elements in the Earth's crust, with an estimated average concentration of 1 part per billion (ppb).

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An oxide of chromium crystallizes with the following unit cell (chromium = gray; oxygen = red)(Figure 1) --CrO3

In order to determine the formula of the oxide, we need to determine the ratio of chromium to oxygen atoms in the unit cell. From the provided unit cell, we can see that there is one chromium atom (gray) in the center of the unit cell, and four oxygen atoms (red) surrounding it. This gives us a ratio of 1:4 chromium to oxygen, which simplifies to a ratio of 1:4 or 1/5. Therefore, the formula of the oxide is CrO4.An oxide is a chemical compound that contains at least one oxygen atom and one other element. Oxides can be either inorganic or organic, depending on the element that is combined with oxygen. Inorganic oxides are compounds composed of a metal and oxygen. They can be further classified as acidic, basic or neutral depending on the oxidation state of the metal atom. Examples of inorganic oxides include water (H2O), carbon dioxide (CO2), sulfur dioxide (SO2), and nitrogen dioxide (NO2)

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Answer:

3 Ca

3 S

12 O

Explanation:

You have 3 moles of Ca(SO4)

Therefore you multiply the subscript of each atom of the compound by 3.

Ca and S have a understood subscript of 1 so there are three of each.

There are 4 oxygen atoms in one mole of CaSO4 so in 3 moles there would be 4*3 so 12

At room temperature I₂(s) is a molecular solid. the correct explanation is : (C)It is not a good conductor of electricity because its valence electrons are localize in bonding and nonbonding pairs.

The Iodine ,  I₂ is the example of the molecular solid. the iodine is the good conductor of the electricity due to the valence electrons that are localized in the bonding pairs and the non bonding pairs. the iodine is the element in the periodic table with the atomic number 53. the iodine is the non metallic solid at the room temperature.

The iodine exists as the diatomic form. the each iodine molecules present as the two iodine as  I₂ . this is the reason it is called as molecular solid.

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Note that statement best explains what is shown in the above-tabularized data is: "The beautyberry increases its chances of reproduction because its berries do not all become ripe at the same time. (Option D)

The statistics in the above table appear to reflect the ripening of berries and the number of blossoms of a plant, presumably called beautyberry. It can be noticed that the amount of ripe berries and blossoms varies each month.

This implies that the beautyberry does not produce all of its berries at once, but rather over the course of several months. This might boost the odds of reproduction by providing a food supply for animals and birds for a longer length of time.

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Using a logarithmic scale with 7 as neutral, lower values are more acidic and higher values are more alkaline, the acidity or alkalinity of a solution is expressed. where c is the number of moles of hydrogen ions present per litre. So pH 2 is 1000 times stronger than pH 5, and vice versa.

For instance, a pH of 2 is 10,000 times more acidic than a pH of 3 and a pH of 5 is 10,000 times more acidic. Ten times as alkaline as a pH of 10 is a pH of 11.

Each whole pH value is ten times more acidic than the next higher value since the pH scale is logarithmic.

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Mole measure the number of elementary entities of a given substance that are present in a given sample. Therefore, 8.0 mol of CuS form when  8.0 mol CuSO[tex]_4[/tex]  reacts.

The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance. We know one mole of any element contains 6.022×10²³ atoms which is also called Avogadro number. The stoichiometry represents the number of moles.

Na[tex]_2[/tex]S + CuSO[tex]_4[/tex]→ Na[tex]_2[/tex]SO[tex]4[/tex] + CuS

moles of  Na[tex]_2[/tex]S  =9.0 mol

moles of  CuSO[tex]_4[/tex]=8.0 mol

Since CuSO[tex]_4[/tex] is limiting reagent

moles of CuS=8.0 mol

Therefore, 8.0 mol of CuS form when  8.0 mol CuSO[tex]_4[/tex]  reacts.

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Answer:

A

Explanation:

because its the only one that can be tested

Helium: The new volume of the balloon is 0.6182 L.

Colorless, odourless , tasteless, inert, non-toxic helium is a monatomic gas. It is the lightest element in the periodic table and the second most abundant element in the universe.

The new volume of the balloon can be calculated using the ideal gas law, which states that PV = nRT, where P is the n represents the number cubic moles of gas, V represents the volume, R is the real gases constant, and the temperature is T.

First, we need to calculate the number of moles of helium in the balloon after the additional 0.670 grams have been added:
n = 0.670 g He/4.003 g/mol = 0.167 mol

The total number of moles in the balloon is now 0.267 mol. We can use the ideal gas law to calculate the new volume:

V = (0.267 mol)(0.0821 L·atm/K·mol)(273 K)/1 atm = 0.6182 L

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Phosphorus, which has the atomic number 15 and is located in period 3 and group 15 of the periodic table.

It is critical to develop a PheDH with specificity and high activity since it is crucial for the manufacture of chiral pharmacological intermediates and the detection of phenylketonuria.

Here, a PheDH gene, pdh, was discovered that encodes a novel BhPheDH with 61.0% similarity to the previously identified PheDH from Microbacterium sp. In comparison to the PheDH from Nocardia sp., the BhPheDH demonstrated superior stability in hot environments (40–70°C) and optimal activity at 60°C and pH 7.0. Additionally, sodium salt has the potential to greatly boost both its activity and thermostability. The residual activity of the BhPheDH was found to be 1.8-fold higher than that of the control group following incubation for 2 hours in 3 M NaCl at 60 °C (without NaCl).

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She changed the mask chemically. Burning of the substance with acid is a chemical change.

A new substance with new qualities is created during burning, which is a chemical alteration that cannot be undone. A chemical change is the transformation of one substance into another, the emergence of new compounds with distinct properties, or any combination of these. It happens when two substances mix to create a new material. Baking soda and vinegar producing carbon dioxide, iron rusting, and wood burning are a few examples of chemical changes. The metabolization of food and the production of amylase from the combining of sugar and saliva are only two examples of the many chemical processes that the body produces.

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Answer:

a) red, blue, and violet

b) orange, yellow, and green

C) red, orange, and yellow

D) blue, indigo, and violet​

The number of moles of a monoprotic acid neutralized is equal to 0.025 mol.

A neutralization reaction can be defined as a reaction in which reaction of an acid and base generates salt and water. When a strong acid and a strong base react the salt can be neither acidic nor basic.

When monoprotic acid HA reacts with NaOH (a strong base), the resulting salt is NaA and water.

HA    +    NaOH   →   NaA  +   H₂O

Given, the concentration of NaOH = 0.544 M

The volume of the NaOH = 45.50 ml = 45.50 × 10⁻³

The number of moles of NaOH, n = M × V = 0.544 × 45.50 × 10⁻³ = 0.025 mol

The number of moles of HA monoprotic acid = moles of NaOH = 0.025 mol

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Thus, Option (C) Glucose has a maximum of 72 C-atoms per gram. The components of fossil fuels are decaying plants and animals.

These fuels may be burned to provide energy and can be found in the crust of the Earth. An example of a fossil fuel is coal, as well as oil and natural gas. Due to the hydrocarbons and other carbon-based compounds they contain, fossil fuels are valuable as energy sources. Any of a class of organic molecules made solely of carbon and hydrogen are known as hydrocarbons. The hydrogen atoms adhere to the carbon atoms, which serve as the "skeleton" or framework. Because they were generated from the petrified, buried remains of plants and animals that once lived millions of years ago, coal, crude oil, and natural gas are all referred to as fossil fuels.

The complete question is- Petroleum is a fossil fuel containing many different carbon compounds. If the carbon atoms in petroleum have been in the ground for 875 million years, what fraction of the initial 14C atoms is still there?

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The zeroth law of thermodynamics describes the state where we can say what about the movement of heat between two substances

The Zeroth Law of thermodynamics is a basic law that describes the state in which two bodies are in thermal equilibrium. It states that if two bodies are in thermal equilibrium with a third body, then they are in thermal equilibrium with each other. In other words, it allows us to determine if two bodies are at the same temperature and if there is no heat flow between them. So, it describes the state where there is no movement of heat between two substances.

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The rate constant at 65 C is k65= 4.8 x 10^-5 s^-1 .Below is the explanation for the answer

To find the rate constant at a different temperature, you can use the Arrhenius equation, which relates the rate constant to the activation energy and the temperature. The equation is:

k = A * e^(-Ea/RT)

where
k is the rate constant,
A is the pre-exponential factor (also known as the frequency factor),
Ea is the activation energy,
R is the universal gas constant,
T is the absolute temperature.

We are given that the activation energy is 83.5 kJ/mol and the rate constant at 45 C is 3.54 x 10^-5 s^-1. To find the rate constant at 65 C, we can substitute these values into the equation and solve for k.

k = A * e^(-Ea/RT)
k = 3.54 x 10^-5 s^-1 * e^(-(83.5 kJ/mol) / (8.314 J/mol*K * (45 + 273.15 K))

However, A is a constant that we don't know. To find the rate constant at 65 C, we can use the fact that the rate constant is proportional to the temperature. Therefore, we can find the ratio of the rate constants at 65 C and 45 C, then multiply it by the rate constant at 45 C to find the rate constant at 65 C.

k65/k45 = (T2/T1)^n
where
k65 is the rate constant at 65 C
k45 is the rate constant at 45 C
T2 is the temperature in Kelvin (65 + 273.15)
T1 is the temperature in Kelvin (45 + 273.15)
n is the order of the reaction, which is 1 in this case

we can find the rate constant at 65 C is:
k65 = k45 (T2/T1)^n
k65 = 3.54 x 10^-5 s^-1 * ( (65 + 273.15) / (45 + 273.15) )^1

k65= 4.8 x 10^-5 s^-1

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Answer is option C) Have low melting points.

Explanation:

As is common knowledge, small molecules make up molecular compounds, and these small molecules are held together by an intermolecular force. The intermolecular tensions in this situation are incredibly weak and simple to overcome when breaking it. Therefore, molecular compounds have low melting and boiling points because of weak intermolecular interactions.

Chemical substances known as molecular compounds assume the shape of distinct molecules. Examples include common substances like carbon dioxide and water. These substances differ significantly from ionic substances like sodium chloride. When metal atoms give up one or more of their electrons to nonmetal atoms, ionic compounds are created. The resultant cations and anions are drawn to one another electrostatically.

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The balanced chemical equation is N₂ + 3 H₂[tex]\rightarrow[/tex] 2 NH₃ which gives the formation of ammonia.

Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.

The first chemical equation was put forth by Jean Beguin in 1615.By making use of chemical equations the direction of reaction ,state of reactants and products can be stated. In the chemical equations even the temperature to be maintained and catalyst can be mentioned.

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Heat engine is a system that converts thermal energy into a form of useful mechanical or electrical energy.

In thermodynamics, the heat engine is a system which is able to convert the heat or thermal energy into mechanical or electrical energy which can be used in order to perform mechanical work. This is achieved by bringing the a particular working substance to a lower state temperature from a higher state temperature.

There are a different types of heat engines in which the Carnot engine possesses the maximum efficiency. Some examples of heat engines are firearms, thermal power station etc.

Hence, the correct option is b. heat engine.

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According to the given chemical equation and stoichiometry of it , 36 moles of H₃PO₄ are formed from 9 moles of P₄O₁₀.

It is the determination of proportions of elements or compounds in a chemical reaction. The related relations are based on law of conservation of mass and law of combining weights and volumes.

Stoichiometry is used in quantitative analysis for measuring concentrations of substances present in the sample.

As per the reaction, 1 mole of P₄O₁₀ produces 4 moles of  H₃PO₄, thus 9 moles of  P₄O₁₀ will produce 9×4=36 moles of H₃PO₄.

Thus,36 moles of H₃PO₄ are formed from 9 moles of P₄O₁₀.

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Answer:36

Explanation:

taking the class just got it right